The present invention generally relates to project management. More specifically, it relates to assessing the performance of a project in terms of its schedule.
Calculating schedule of a project based on earned value management (EVM) is a primary factor used to track projects. As is known in the art, EVM is a technique where a project plan, actual work planned till date and work-completed value are monitored to see whether a project is on track. Thus, typically, the essential features of an EVM implementation include:
a. a project plan identifying the work to be accomplished;
b. an estimated value of work to be accomplished within a fixed period, called planned value (PV); and
c. a budgeted cost of work performed, called earned value (EV).
Based on the EV and the PV defined above, for any project, an index called a schedule performance index (SPI) is calculated that helps in assessing whether the project is on schedule. Typically, the SPI is calculated using the formula SPI=(EV/PV). An SPI of 1 indicates that the project is on schedule, an SPI greater than 1 indicates that the project is ahead of schedule, while an SPI less than 1 indicates that the project is behind schedule.
Though the SPI gives a fair idea of how the project is progressing, it is not fully accurate. This is because the SPI does not consider the time factor while arriving at the index. For example, consider a project that was scheduled to finish in 16 weeks but instead, finished in 17 weeks. In this case, at the end of 17 weeks, the EV will be equal to PV, and hence, the SPI will be equal to 1. This is misleading, because though the SPI shows a value of 1, which indicates that the project is on schedule, the project was actually delayed by one week. As in this case, the indication provided by the SPI is usually on the upper side, which can be risky when followed blindly. This limitation is not just at the end of the project but exists throughout the execution of the project, thereby providing a misleading index.
In light of the foregoing, there exists a need for an improved schedule performance index that considers the time factor in assessing the progress of a project. Further, this index should be accurate throughout the duration of the project.